Electronic systems and circuits have made a significant contribution towards the advancement of modern society and are utilized in a number of applications to achieve advantageous results. Numerous electronic technologies such as digital computers, calculators, audio devices, video equipment, and telephone systems have facilitated increased productivity and reduced costs in analyzing and communicating data, ideas and trends in most areas of business, science, education and entertainment. A number of these activities involve responding to user commands. Systems that permit utilization of vocal commands require the commands to be discernible and differentiating commands from other environmental audio noise and interference can be problematic, especially distinguishing audio program content from user commands.
Numerous electronic devices include systems that emit audio sounds. These systems typically provide a number of advantageous benefits, including enhanced user experience. Program audio content, such as music, can be very pleasing by itself. Alternatively, program audio content can also be presented in conjunction with visual information. For example, audio content in television programs or video games often includes sound effects for complementing visual presentations and enhancing user emersion in the activity. These and other audio systems are often controlled by user commands or directions.
Systems that respond to user audio commands often offer a number of potential advantageous benefits. Users usually find issuing vocal commands convenient and a familiar technique to communicate instructions. In addition, vocal commands are often intuitive and easy to comprehend. For example, if a user wants a device such as a personal video recorder to cease an activity or operation the user says the word “stop”. Vocal command recognition systems often reduce the need for arduous input by hand and can free up hands for relaxation or other activities such as controlling a game console joystick with minimal interruption for generic system control input. However, many systems that include features for emitting audio program content while also attempting to utilize vocal command recognition often encounter audio feedback that can cause problems.
One difficulty in using voice recognition technology to control video and audio systems is the audio feedback from the video or audio system. For example, if a CD is playing a song and the song includes the lyric “stop” that is picked up by the voice recognition of the control system, the control system could potentially misinterpret the lyric “stop” as a user command and stop the CD playing. In addition, the audio feedback can produce more generic interference that makes proper interpretation of user commands more difficult. For example, generic audio interference can introduce additional audio signals that interfere with vocal user command signals making it difficult for a voice recognition algorithm to properly distinguish the user commands.